Texting is hanging up

My text messaging is hanging up; in other words, when I send a message, the app freezes the phone for upwards of a minute....or, after I read a message, I'll pull up my messages again, where the message I just read shows as unread. This too causes the entire phone to lock up.

My text messaging is hanging up; in other words, when I send a message, the app freezes the phone for upwards of a minute....or, after I read a message, I'll pull up my messages again, where the message I just read shows as unread. This too causes the entire phone to lock up.

My messaging app also hangs after I send a text, then back out to the thread list. If I tap on another thread, it can take 10 or so seconds just to respond, and afterwards the phone is very sluggish for several minutes.